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Will IR help find dampness in attics?


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I did a pre-listing inspection a couple of weeks ago. While I usually walk (crawl, squirm) as much of the attic as I can, the relatively low slope roof on this one made it hard to move around much. I found lots of stains on the trusses from previous leaks, and a couple of spots where the plywood sheathing was a little soft, but my trusty moisture meter (Tramex ME+) said it was dry.

I walked the whole roof on the outside. Shingles about a year old, original flashings, but in good shape and re-fastened and caulked where needed. Client said the roofer had replaced any questionable sheathing when the shingles were replaced. Everything looked good, and that's what I put in my report.

An inspector hired by the eventual buyer reported that the roof was leaking, some of the sheathing, framing and insulation was damp, and the buyer negotiated for a reduction in the sale price because of this.

Now, I'm a newby, just over 300 inspections under my belt, this concerns me. Someone a lot smarter than me wrote "learn from the mistakes of others, 'cause you won't live long enough to make them all yourself". So far, I seem to be learning too many from my own.

How did I miss the wet areas? How did the other inspector find them? Would an IR camera help check for moisture in those areas I can't normally get close to?

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Maybe. If the top of the drywall ceiling is damp, you may get a thermal signature looking at the ceiling from below. The moisture evaporating takes heat with it, so the area may show as cool. If the drywall itself is damp, it will change temperature more slowly than dry areas of the same material around it, so may show as warm or cool depending on which way the heat is flowing. You always want a delta T between the two areas (inside vs. attic in this case) in order to inspect with IR.

Truth is, you can see stuff on ceilings with IR, but you always reach for your moisture meter to check thermal anomalies. Sounds like you already did some moisture metering and found nothing. With IR you might narrow down the areas to look at so the inspection might go more quickly, but you still need to rely on the meter in most cases.

Maybe the other guy is blowing smoke. Did you read the report, or just get third-hand info about what went down?

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How do you know you missed an active leak? Sounds like the others dude's definitions of a active leak and yours are two different things. Who knows, he could have called all the old staining leaks.

I've been using a Fluke IR for about a year. Taking a six thousand dollar IR camera into the spots I go into an attic won't happen.

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As you said David, I only heard about it from the realtor, who's wondering who is right about the leak(s).

Has anyone had positive results finding wet sheathing, framing, insulation, etc. by scanning with an IR camera from within the attic? Perhaps I'm looking for a "magic bullet" that doesn't exist? It would seem from clients' comments that possible roof leaks are one of their biggest concerns. I just don't feel my visual inspection is sufficient, considering there are areas in most attics where I can't get close enough to touch, probe with a meter, even see clearly. I know, our standards say "visual inspection".

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Did it rain?

Really, that may be the question you need to ask. An IR or moisture meter won't tell you squat if the building has dried out since it rained.

You can see stains (usually) whether wet or dry. The first and best inspection is visual and all the other tools in the bag are just to confirm your suspicions.

All the whizz bang tools in the world can't tell you if the roof leaks unless it is leaking or at least still wet when you are there.

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